The synthesis of certain dihydrocarbylsilyl-bridged zirconocene complexes and their use as polymerization catalyst components have been reported heretofore. See for example U. Stehling et al., Organometallics 1994, 13, 964-970. Rohrmann et al. U.S. Pat. No. 5,455,366 issued Oct. 3, 1995, describes multistep processes for producing a variety of metallocenes having benzo-fused indenyl derivatives as ligands. These materials are also shown to have utility in the formulation of polymerization catalysts.
While workable, these prior processes are deemed best suited for laboratory-scale operations. Thus a need exists for a simplified process which can be used to make desired bridged metallocenes, such as dihydrocarbylsilyl-bridged zirconocene complexes, in acceptable yields in large scale production facilities. One of the key steps in any such process is the interaction between a protonated bridged ligand and a metal tetrahalide salt to form the desired bridged metallocene. Unfortunately, this reaction tends to be tedious, difficult and time-consuming.